環硼氮烷

環硼氮烷
	IUPAC名; 1,3,5,2,4,6-Triazatriborinane; 1,3,5,2,4,6-三氮雜三硼烷（僅預選）
別名	環硼氮六烷; 硼氮六環; 無機苯; 硼嗪
識別
CAS號	6569-51-3
PubChem	138768
ChemSpider	122374
SMILES	[BH-]1-[NH+]=[BH-]-[NH+]=[BH-]-[NH+]=1;
InChI	1/B3H6N3/c1-4-2-6-3-5-1/h1-6H;
InChIKey	BGECDVWSWDRFSP-UHFFFAOYAU
ChEBI	33119
性質
化學式	B3H6N3
摩爾質量	80.50 g·mol⁻¹
外觀	無色液體
密度	0.81 g/cm3
熔點	−58 °C（215 K）
沸點	53 °C（326 K）
磁化率	-49.6·10−6 cm3/mol
危險性
NFPA 704	2 2 1
	若非註明，所有數據均出自標準狀態（25 ℃，100 kPa）下。

環硼氮烷（英語：Borazine）是一種非極性^[2]的無機化合物，化學式為B₃N₃H₆。該環狀化合物的結構中有三個B-H單元和三個N-H單元交替出現。它是苯的等電子體，故有時被稱為無機苯。與苯一樣，環硼氮烷是一種具有芳香氣味的無色液體。^[3]

合成

在1926年，化學家Alfred Stock和Erich Pohland通過乙硼烷與氨的反應合成了環硼氮烷。^[4]

環硼氮烷可以通過乙硼烷和氨按1:2比例在250-300°C下反應合成，轉化率為50%。

3 B₂H₆ + 6 NH₃ → 2 B₃H₆N₃ + 12 H₂

更有效的途徑為硼氫化鈉與氯化銨反應：^[5]

6 NaBH₄ + 3 (NH₄)₂SO₄ → 2 B₃N₃H₆ + 3 Na₂SO₄ + 18 H₂

在兩步法中，三氯化硼先轉化為三氯環硼氮烷：

3 BCl₃ + 3 NH₄Cl → B₃Cl₃H₃N₃ + 9 HCl

再使用硼氫化鈉還原：

2 B₃Cl₃H₃N₃ + 6 NaBH₄ → 2 B₃H₆N₃ + 3 B₂H₆ + 6 NaCl

結構

環硼氮烷與苯為等電子體，具有相似的性質，因此有時也被稱為無機苯。由於硼和氮之間的電負性差異，它們並不完全相同。X射線晶體學結構測定表明，環硼氮烷內的鍵長都等於1.429Å，與苯性質相同。^[6]然而，環硼氮烷並沒有形成完美的六邊形。硼原子的鍵角為117.1°，氮原子的鍵角為122.9°，使分子具有D_3h對稱點群。

與氮的電負性（鮑林標度3.04）相比，硼的電負性（2.04）以及硼的缺乏電子和氮的孤對電子有利於環硼氮烷的內消旋體結構。

其中硼表現為路易斯酸，氮表現為路易斯鹼。

芳香性

由於環硼氮烷與苯的相似性，因此對其芳香性進行了許多計算和實驗分析。環硼氮烷的π電子數遵從4n+2規則，B-N鍵長相等，表明其可能是芳香族化合物。然而硼和氮之間的電負性差異導致電荷共享不均，從而導致鍵具有更大的離子特性，因此預計其電子離域比全碳類似物差。環硼氮烷的標準生成焓變化量ΔH_f為−531 kJ/mol，熱穩定性非常好。

自然鍵軌道

自然鍵軌道理論（NBO）分析表示環硼氮烷中的芳香性較弱。^[7]在NBO模型中，環中的B-N鍵略微偏離原子核軸，B和N的電荷差異較大。核獨立化學位移（NCS）分析提供了一些進一步的證據，證明基於B-N π鍵對磁屏蔽的貢獻的芳香性。基於NBO軌道的計算表明，該 π 鍵允許產生微弱的環電流，在一定程度上抵消了環硼氮烷中心模擬的磁場。一個小的環電流確實表明存在一些離域現象。

電子局域函數

電子局域函數（ELF）對環硼氮烷中的成鍵進行拓撲分析，表明環硼氮烷可以認為是芳香族化合物。然而，基於電子盆地的分叉值差異，環硼氮烷中的鍵合比苯的鍵合離域性更差。較大的分叉值表示電子離域性較好，有人認為當該分岔值大於0.70時，其離域性就足以指定化合物為芳香族化合物。^[8]對於苯，該值為0.91，但環硼氮烷的π系統在ELF值為0.682時分叉。^[9]這是由於B和N之間的電負性差異，產生鍵的相互作用力比苯中C-C的相互作用力弱，導致電子在B-H和N-H單元上的定域化增加。分叉值略低於0.70的極限值，表明其有中等的芳香性。

性質與用途

水解

環硼氮烷很容易水解，生成硼酸、氨和氫氣。

聚合

聚環硼氮烷

在70°C下加熱環硼氮烷會放出氫氣並形成聚環硼氮烷：

n B₃N₃H₆ → [B₃N₃H₄]_n

鹵化氫和鹵素

環硼氮烷與氯化氫形成加成物：

B₃N₃H₆ + 3 HCl → B₃Cl₃N₃H₉

環硼氮烷與氯化氫的加成反應

B₃Cl₃N₃H₉ + NaBH₄ → (BH₄N)₃

使用硼氫化鈉還原

環硼氮烷與溴的加成反應無需催化劑。其對硼進行親核攻擊，對氮進行親電攻擊。

陶瓷前體

氮化硼可通過將聚環硼氮烷加熱至1000°C製備。^[5]

環硼氮烷也是其他潛在陶瓷的起始材料，例如碳氮化硼。環硼氮烷也可用作前體，在銅^[10]、鉑^[11]、鎳^[12]、鐵^[13]等催化表面使用化學氣相沉積法（CVD）生長六方氮化硼（h-BN）薄膜和單層。

其他用途

聚環硼氮烷已被提議作為氫燃料電池汽車應用的回收儲氫介質，使用「單罐」工藝進行消化和還原以重新生成硼烷氨。^[14]

在其他B-N型化合物中，混合的氨基-硝基取代環硼氮烷已被預測優於碳基炸藥，如CL-20。^[15]^[16]

參考資料

^ Front Matter. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014: 968. ISBN 978-0-85404-182-4. doi:10.1039/9781849733069-FP001.
^ Nelson, Ralph; et al. Selected values of electric dipole moments for molecules in the gas phase (PDF). American National Bureau of Standards. September 1, 1967, (10): 17 [2023-01-25]. （原始內容存檔 (PDF)於2018-06-08）.
^ Duward Shriver; Peter Atkins. Inorganic Chemistry Fifth. New York: W. H. Freeman and Company. 2010: 328. ISBN 978-1429218207.
^ Stock A, Pohland E. Borwasserstoffe, VIII. Zur Kenntnis des B₂H₆ und des B₅H₁₁ [Boric acid solution, VIII Regarding knowledge of B₂H₆ and B₅H₁₁]. Berichte. October 1926, 59 (9): 2210–2215. doi:10.1002/cber.19260590906 （德語）.
^ ^5.0 ^5.1 Wideman, Thomas; Fazen, Paul J.; Lynch, Anne T.; Su, Kai; Remsen, Edward E.; Sneddon, Larry G. Borazine, Polyborazylene, β-Vinylborazine, and Poly(β-Vinylborazine). Borazine, Polyborazylene, β‐Vinylborazine, and Poly(β‐Vinylborazine). Inorganic Syntheses 32. 1998: 232–242. ISBN 9780470132630. doi:10.1002/9780470132630.ch39.
^ Boese R, Maulitz AH, Stellberg P. Solid-State Borazine: Does it Deserve to be Entitled "Inorganic Benzene"?. Chemische Berichte. 1994, 127 (10): 1887–1889. doi:10.1002/cber.19941271011.
^ Shen W, Li M, Li F, Wang S. Theoretical study of borazine and its derivatives. Inorg. Chim. Acta. 2007, 360 (2): 619–624. doi:10.1016/j.ica.2006.08.028.
^ Santos JC, Tiznado W, Contreras R, Fuentealba P. Sigma-pi separation of the electron localization function and aromaticity. The Journal of Chemical Physics. January 2004, 120 (4): 1670–3. Bibcode:2004JChPh.120.1670S. PMID 15268298. doi:10.1063/1.1635799. hdl:10533/175272  .
^ Islas R, Chamorro E, Robles J, Heine T, Santos JC, Merino G. Borazine: to be or not to be aromatic. Struct. Chem. 2007, 18 (6): 833–839. S2CID 95098134. doi:10.1007/s11224-007-9229-z.
^ Kidambi PR, Blume R, Kling J, Wagner JB, Baehtz C, Weatherup RS, et al. In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper. Chemistry of Materials. November 2014, 26 (22): 6380–6392. PMC 4311958  . PMID 25673919. doi:10.1021/cm502603n.
^ Kim G, Jang AR, Jeong HY, Lee Z, Kang DJ, Shin HS. Growth of high-crystalline, single-layer hexagonal boron nitride on recyclable platinum foil. Nano Letters. April 2013, 13 (4): 1834–9. Bibcode:2013NanoL..13.1834K. PMID 23527543. doi:10.1021/nl400559s.
^ Chatterjee S, Luo Z, Acerce M, Yates DM, Johnson AT, Sneddon LG. Chemical Vapor Deposition of Boron Nitride Nanosheets on Metallic Substrates via Decaborane/Ammonia Reactions. Chemistry of Materials. 2011-10-25, 23 (20): 4414–4416. ISSN 0897-4756. doi:10.1021/cm201955v （英語）.
^ Caneva S, Weatherup RS, Bayer BC, Brennan B, Spencer SJ, Mingard K, et al. Nucleation control for large, single crystalline domains of monolayer hexagonal boron nitride via Si-doped Fe catalysts. Nano Letters. March 2015, 15 (3): 1867–75. Bibcode:2015NanoL..15.1867C. PMC 4358078  . PMID 25664483. doi:10.1021/nl5046632.
^ Davis BL, Dixon DA, Garner EB, Gordon JC, Matus MH, Scott B, Stephens FH. Efficient regeneration of partially spent ammonia borane fuel. Angewandte Chemie. 2009, 48 (37): 6812–6. OSTI 960522. PMID 19514023. doi:10.1002/anie.200900680.
^ Koch EC, Klapötke TM. Boron-Based High Explosives.. Propellants, Explosives, Pyrotechnics. 2012, 37 (3): 335–344. doi:10.1002/prep.201100157.
^ Kervyn S, Fenwick O, Di Stasio F, Shin YS, Wouters J, Accorsi G, et al. Polymorphism, fluorescence, and optoelectronic properties of a borazine derivative. Chemistry. June 2013, 19 (24): 7771–9 [2023-01-25]. PMID 23616404. S2CID 9774352. doi:10.1002/chem.201204598  . （原始內容存檔於2021-02-21）.

延伸閱讀

Sneddon LG, Mirabelli MG, Lynch AT, Fazen PJ, Su K, Beck JS. Polymeric precursors to boron based ceramics (PDF). Pure Appl. Chem. 1991, 63 (3): 407–410 [2023-01-25]. S2CID 53629042. doi:10.1351/pac199163030407. （原始內容存檔 (PDF)於2012-02-08）.
Jeon JK, Uchimaru Y, Kim DP. Synthesis of novel amorphous boron carbonitride ceramics from the borazine derivative copolymer via hydroboration. Inorganic Chemistry. August 2004, 43 (16): 4796–8. PMID 15285647. doi:10.1021/ic035254a.
Paetzold P. New perspectives in boron-nitrogen chemistry - I (PDF). Pure Appl. Chem. 1991, 63 (3): 345–350 [2023-01-25]. S2CID 53659373. doi:10.1351/pac199163030345. （原始內容存檔 (PDF)於2012-07-16）.
Islas R. Borazine: to be or not to be aromatic. Structural Chemistry. 2007, 18 (6): 833–839. S2CID 95098134. doi:10.1007/s11224-007-9229-z.

[iupac2013-1] Front Matter. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014: 968. ISBN 978-0-85404-182-4. doi:10.1039/9781849733069-FP001.

[2] Nelson, Ralph; et al. Selected values of electric dipole moments for molecules in the gas phase (PDF). American National Bureau of Standards. September 1, 1967, (10): 17 [2023-01-25]. （原始內容存檔 (PDF)於2018-06-08）.

[3] Duward Shriver; Peter Atkins. Inorganic Chemistry Fifth. New York: W. H. Freeman and Company. 2010: 328. ISBN 978-1429218207.

[4] Stock A, Pohland E. Borwasserstoffe, VIII. Zur Kenntnis des B₂H₆ und des B₅H₁₁ [Boric acid solution, VIII Regarding knowledge of B₂H₆ and B₅H₁₁]. Berichte. October 1926, 59 (9): 2210–2215. doi:10.1002/cber.19260590906 （德語）.

[IS-5] 5.0 ^5.1 Wideman, Thomas; Fazen, Paul J.; Lynch, Anne T.; Su, Kai; Remsen, Edward E.; Sneddon, Larry G. Borazine, Polyborazylene, β-Vinylborazine, and Poly(β-Vinylborazine). Borazine, Polyborazylene, β‐Vinylborazine, and Poly(β‐Vinylborazine). Inorganic Syntheses 32. 1998: 232–242. ISBN 9780470132630. doi:10.1002/9780470132630.ch39.

[6] Boese R, Maulitz AH, Stellberg P. Solid-State Borazine: Does it Deserve to be Entitled "Inorganic Benzene"?. Chemische Berichte. 1994, 127 (10): 1887–1889. doi:10.1002/cber.19941271011.

[7] Shen W, Li M, Li F, Wang S. Theoretical study of borazine and its derivatives. Inorg. Chim. Acta. 2007, 360 (2): 619–624. doi:10.1016/j.ica.2006.08.028.

[8] Santos JC, Tiznado W, Contreras R, Fuentealba P. Sigma-pi separation of the electron localization function and aromaticity. The Journal of Chemical Physics. January 2004, 120 (4): 1670–3. Bibcode:2004JChPh.120.1670S. PMID 15268298. doi:10.1063/1.1635799. hdl:10533/175272  .

[9] Islas R, Chamorro E, Robles J, Heine T, Santos JC, Merino G. Borazine: to be or not to be aromatic. Struct. Chem. 2007, 18 (6): 833–839. S2CID 95098134. doi:10.1007/s11224-007-9229-z.

[10] Kidambi PR, Blume R, Kling J, Wagner JB, Baehtz C, Weatherup RS, et al. In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper. Chemistry of Materials. November 2014, 26 (22): 6380–6392. PMC 4311958  . PMID 25673919. doi:10.1021/cm502603n.

[11] Kim G, Jang AR, Jeong HY, Lee Z, Kang DJ, Shin HS. Growth of high-crystalline, single-layer hexagonal boron nitride on recyclable platinum foil. Nano Letters. April 2013, 13 (4): 1834–9. Bibcode:2013NanoL..13.1834K. PMID 23527543. doi:10.1021/nl400559s.

[12] Chatterjee S, Luo Z, Acerce M, Yates DM, Johnson AT, Sneddon LG. Chemical Vapor Deposition of Boron Nitride Nanosheets on Metallic Substrates via Decaborane/Ammonia Reactions. Chemistry of Materials. 2011-10-25, 23 (20): 4414–4416. ISSN 0897-4756. doi:10.1021/cm201955v （英語）.

[13] Caneva S, Weatherup RS, Bayer BC, Brennan B, Spencer SJ, Mingard K, et al. Nucleation control for large, single crystalline domains of monolayer hexagonal boron nitride via Si-doped Fe catalysts. Nano Letters. March 2015, 15 (3): 1867–75. Bibcode:2015NanoL..15.1867C. PMC 4358078  . PMID 25664483. doi:10.1021/nl5046632.

[14] Davis BL, Dixon DA, Garner EB, Gordon JC, Matus MH, Scott B, Stephens FH. Efficient regeneration of partially spent ammonia borane fuel. Angewandte Chemie. 2009, 48 (37): 6812–6. OSTI 960522. PMID 19514023. doi:10.1002/anie.200900680.

[15] Koch EC, Klapötke TM. Boron-Based High Explosives.. Propellants, Explosives, Pyrotechnics. 2012, 37 (3): 335–344. doi:10.1002/prep.201100157.

[16] Kervyn S, Fenwick O, Di Stasio F, Shin YS, Wouters J, Accorsi G, et al. Polymorphism, fluorescence, and optoelectronic properties of a borazine derivative. Chemistry. June 2013, 19 (24): 7771–9 [2023-01-25]. PMID 23616404. S2CID 9774352. doi:10.1002/chem.201204598  . （原始內容存檔於2021-02-21）.

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